The Senate approved a House-passed resolution Tuesday directing President Donald Trump to withdraw U.S. armed forces from hostilities against Iran, after four Republican senators broke ranks in a rare vote to undercut the president's commander-in-chief authority.

Senate Delivers Rare War Powers Rebuke

The Senate voted 50-48 to approve the measure, Reuters reported. The House passed it earlier this month, 215-208. It marked the first time both chambers had approved a resolution directing a president to remove U.S. forces from hostilities since Congress enacted the War Powers Resolution in 1973.

The measure came straight to the Senate floor for an up-or-down vote. It does not require Trump's signature because it is a concurrent resolution.

Under the 1973 law, Congress intended such resolutions to end military operations. But legal experts say the issue remains unsettled. No war powers resolution had previously passed both chambers, and a 1983 Supreme Court ruling said such a measure must go to the president for signature or veto to have legal effect.

The White House has argued that the War Powers Act is unconstitutional and not binding. A White House official told Reuters the vote had no significance because the resolution does not go to Trump and carries no force of law. The official also said hostilities ended with an April 7 ceasefire.

MarketDash separately reached out to the White House for comment but did not hear back at the time of publishing.

Four Republicans Join Democrats Against Trump

Sens. Rand Paul (R-Ky.), Susan Collins (R-Maine), Lisa Murkowski (R-Alaska) and Bill Cassidy (R-La.) voted with Democrats. The same four Republicans voted last week to discharge a similar resolution from committee, but the effort failed due to Democratic attendance issues.

Sen. Thom Tillis (R-N.C.), who had said he was open to arguments from both sides, voted no. Sens. Mitch McConnell (R-Ky.) and Dave McCormick (R-Pa.) missed the vote after previously opposing Iran war powers measures. Sen. John Fetterman (D-Pa.) was the only Democrat to vote against the resolution.

Sen. Bernie Sanders (I-Vt.) welcomed the vote, saying Congress had finally asserted its constitutional role over war powers. "Congress finally did what should have been done months ago: voted to demand Trump end his war with Iran," Sanders wrote on X. "The Constitution is clear: Presidents cannot unilaterally take us to war. That's the responsibility of Congress. About time Congress finally accepted its responsibility."

Four House Republicans earlier joined every Democrat in backing the measure, including Reps. Thomas Massie (R-Ky.), Brian Fitzpatrick (R-Pa.), Tom Barrett (R-Mich.) and Warren Davidson (R-Ohio).

Iran Vote Adds Pressure On Trump

The symbolic setback comes as the administration is expected to seek tens of billions of dollars for the war. Some Republicans also recently balked at Trump's $1.8 billion "antiweaponization" fund and stalled a $70 billion immigration bill.

A Reuters/Ipsos poll released Tuesday found that only about one in four Americans believe the Iran war was worth its costs. Most also doubt a truce with Tehran will last.

The Trump administration is trying to negotiate a peace agreement with Iran. Congressional support for the resolution is likely to increase pressure on Trump not to resume attacks, something he has threatened to do if negotiations falter.